Study of the Structure and the Dynamics of Ge-Sb-Te Liquids
Abstract: Some liquids Ge-Te, such as the eutectic alloy Ge15Te85, exhibit a decrease of their volume when the temperature increases just above their melting point. This negative thermal expansion (NTE) is accompanied with thermodynamic anomalies and important changes in the electrical conductivity. Simulations have shown that this NTE is associated with a distortion of the octahedral structure around Ge atoms. Conversely, it was shown that liquidGe15Sb85 does not exhibit any anomaly. This thesis focused on the effect of substituting Sb to Te in Ge15Te85. The total structure factors were measured by neutron scattering on the 7C2 spectrometer at the LLB (Laboratory Léon Brillouin, Saclay). The analysis of the results fromthis experiment suggested that Sb does not kill off the anomaly. Indeed, when Sb is added to Ge15Te85, the melting temperature of the alloy is increased. As a result, the anomaly that could be seen in the liquid for Ge15Te85, is moved into the overcooled area for Ge15(SbxTe1-x)85 alloys with 0
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